The electromigration effect refers to the transport of material of a conductor (e.g., a metal wire) caused by a gradual movement of ions in the conductor. The transport of material occurs when momentum is transferred between conducting electrons and diffusing metal atoms of the conductor. This movement of material within the conductor can lead to a thinning of the conductor and eventually complete failure (i.e., disconnected wire).
Additionally, electromigration effects become a greater difficulty in integrated circuits as designs achieve higher signal switching frequency and smaller metal geometries. The greater difficulty is caused by a higher flow of electrons through the smaller metal geometries, which results in increased migration of the conductor and, therefore, faster or more frequent failure. Existing remedies to mitigate electromigration effects within integrated circuits quickly become inadequate to resolve dramatically increasing numbers of electromigration fails on circuits with smaller metal geometries and higher switching frequencies. Existing remedies are also limited by increasingly stringent and complex design rules set by integrated circuit manufacturers as technologies advance over time.